Work is proposed in three areas of ultracentrifuge methodological research. The studies include the further development of difference sedimentation equilibrium for measurement of small differences in molecular weight and the easy measurement of partial specific volumes. Work is proposed to continue investigation of active enzyme sedimentation velocity to improve this method. Finally, the properties of difference sedimentation velocity experiments will be explored. Several studies are proposed concerning the frictional properties of proteins and other biologial molecules. It is planned to develop a method for further determination of protein shapes from hydrodynamic behavior using the correlation of frictional properties and accessible surface area. It is proposed to investigate association-dissociation reactions of proteins of known structure to determine the energetics of hydrogen bonds, hydrophobic bonds and the like. The objective of this research is to establish an independent measure of these forces within proteins. We propose to analyze the packing density within proteins to investigate the propagation of motion and force within secondary and tertiary structures. We plan to continue investigations of the evolutionary origins of the trypsin-related blood clotting enzymes and their zymogens and to investigate the origins of the immunoglobins by studies of primary structure.